<template>
  <div class="cpdf" id="cpdf">
    <!--    <top-normal-bar normalTitle="合同查看"></top-normal-bar>-->
    <div class="center">
      <canvas id="the-canvas" class="canvasstyle"></canvas>
      <div class="contor">
        <el-button @click="prev">上一页</el-button>
        <span style="padding: 0 10px"><span v-text="page_num"></span> / <span v-text="page_count"></span></span>
        <el-button @click="next">下一页</el-button>
      </div>
    </div>
  </div>
</template>

<script>
import PDFJS from 'pdfjs-dist'

export default {
  name: 'PdfPlayer',
  props: {
    resourceUrl: {
      type: String,
      default: 'http://8.134.32.9:9000/arbook/pdf/504924501439494.pdf'
    }
  },
  data() {
    return {
      pdfDoc: null, //pdfjs 生成的对象
      pageNum: 1,//
      pageRendering: false,
      pageNumPending: null,
      scale: 1,//放大倍数
      page_num: 0,//当前页数
      page_count: 0,//总页数
      maxscale: 2,//最大放大倍数
      minscale: 0.8//最小放大倍数
    }
  },
  methods: {
    renderPage(num) { //渲染pdf
      let vm = this
      this.pageRendering = true
      let canvas = document.getElementById('the-canvas')
      // Using promise to fetch the page
      this.pdfDoc.getPage(num).then(function(page) {
        var viewport = page.getViewport(vm.scale)
        //alert(vm.canvas.height)
        canvas.height = viewport.height
        canvas.width = viewport.width

        // Render PDF page into canvas context
        var renderContext = {
          canvasContext: vm.ctx,
          viewport: viewport
        }
        var renderTask = page.render(renderContext)

        // Wait for rendering to finish
        renderTask.promise.then(function() {
          vm.pageRendering = false
          if (vm.pageNumPending !== null) {
            // New page rendering is pending
            vm.renderPage(vm.pageNumPending)
            vm.pageNumPending = null
          }
        })
      })
      vm.page_num = vm.pageNum

    },
    addscale() {//放大
      if (this.scale >= this.maxscale) {
        return
      }
      this.scale += 0.1
      this.queueRenderPage(this.pageNum)
    },
    minus() {//缩小
      if (this.scale <= this.minscale) {
        return
      }
      this.scale -= 0.1
      this.queueRenderPage(this.pageNum)
    },
    prev() {//上一页
      let vm = this
      if (vm.pageNum <= 1) {
        return
      }
      vm.pageNum--
      vm.queueRenderPage(vm.pageNum)
    },
    next() {//下一页
      let vm = this
      if (vm.pageNum >= vm.page_count) {
        return
      }
      vm.pageNum++
      vm.queueRenderPage(vm.pageNum)
    },
    closepdf() {//关闭PDF
      this.$emit('closepdf')
    },
    queueRenderPage(num) {
      if (this.pageRendering) {
        this.pageNumPending = num
      } else {
        this.renderPage(num)
      }
    }
  },
  computed: {
    ctx() {
      let id = document.getElementById('the-canvas')
      return id.getContext('2d')
    }
  },
  mounted() {
    let vm = this
    PDFJS.getDocument(vm.resourceUrl).then(function(pdfDoc_) { //初始化pdf
      vm.pdfDoc = pdfDoc_
      vm.page_count = vm.pdfDoc.numPages
      vm.renderPage(vm.pageNum)
    })
  }
}

</script>

<style lang="scss">
.cpdf {
  background-color: rgba(0, 0, 0, .5);
  width: 100%;
  height: 100%;
  z-index: 99999;
  display: flex;
  justify-content: center;
  align-items: center;

  .center {
    text-align: center;
    height: 100%;
    overflow: auto;
    padding-top: 20px;

    .contor {
      margin-bottom: 10px;
    }
  }
}
</style>
